1. Field of the Invention
This invention relates generally to electro-optical scanning systems and, more particularly, to scanning systems that involve indirect viewing (via a television intermediary) of an image field at a plurality of magnifications.
2. Discussion of the Related Art
Automatic systems for scanning and analyzing microscope field images have been developed, the most notable being the automatic scanning and examination of blood cells. However, the interpretive ability of visual examination by a human observer is still generally required for accurate analysis, particularly with respect to, for example, histological specimens. Typical microscopic examination of a specimen involves the examination of the specimen by direct viewing through oculars using various objective elements to provide a plurality of magnifications. Different magnifications can be accomplished by selectively positioning the various objective lenses located in a turret immediately over the specimen. By rotation of the turret, objective lenses of different magnifications can be used to examine the specimen. The general procedure is to scan a specimen at relatively low magnification and then to use higher magnification to examine selected specimen areas in detail.
The direct viewing process, through widely utilized, has several disadvantages. First, the microscope field images at a plurality of magnifications cannot be viewed simultaneously. In addition, the manual positioning of the turret containing the plurality of lenses frequently makes more detailed examination of a selected specimen region ambiguous because of the lack of knowledge of the precise spatial relationship between the fields viewed at different magnifications. Furthermore, viewing of a specimen through an ocular for a long period of time can be tiring. Finally, photography and storage of images can require a separate operation, frequently disturbing the examination routine.
Similar problems can be found in examination of images recorded on high-resolution photographic emulsions such as those used in aerial photography and in the storage of documents on microfiche. Typically, a search for certain selected information is conducted at relatively low magnification. Examination of areas of the low magnification image in which the selected information may be present can then be performed at a higher magnification until the presence of the selected information is confirmed or rejected.
A need has therefore been felt for a microscope scanning system that can view and present to the user images of a specimen under a plurality of magnifications simultaneously, can accurately determine spatial the relationships between the plurality of images and can conveniently store and retrieve the images for future examination and for comparison purposes.